Anatomy 4: Anatomy of Cranial Nerves

Question 1

For CNI, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 1

In olfactory mucosa in nasal cavity
Synapse in olfactory bulb, and pass to olfactory tract
NO CONNECTION

Question 2

Outline how you would go about testing CNI

Answer 2

Smell while covering contralateral side`

Question 3

For CNII, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 3

Neurones of retina travel posteriorly via optic nerve to the orbit
Pass from the optic chiasm to the optic tract
Diencephalon

Question 4

Outline how you would go about testing CNII

Answer 4

Visual acuity (Snellen)
Colour (Ishihara plates)
Fields (4 quadrants)
Reflexes (Pupillary light reflexes)
Fundoscopy

Question 5

For CNIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 5

SOF into orbit and supply all extraocular muscles except 2, PSs synapse in ciliary ganglion
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)

Question 6

Outline how you would go about testing CNIII

Answer 6

Light reflexes via a torch (PS)

Question 7

For CNIV, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 7

SOF into orbit and supply SO muscle
Lateral wall of cavernous sinus (orbit)
Mesencephalon (midbrain)

Question 8

Outline how you would go about testing CNIV

Answer 8

H test (in and down)

Question 9

For CNVI, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 9

SOF into orbit and supply LR muscle
Cavernous sinus to orbit
Pontomedullary junction

Question 10

Outline how you would go about testing CNVI

Answer 10

H test (out)

Question 11

For CNVIII, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 11

Axons from cochlear and vestibular apparatus
Posteromedially from IAM to PM junction
Pontomedullary junction

Question 12

Outline how you would go about testing CNVIII

Answer 12

Rinnie and Weber tests

Question 13

For CNXI, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 13

Axons supply SCMD, travel across posterior triangle to trapezius
Foramen magnum to jugular foramen
Cervical spinal cord

Question 14

Outline how you would go about testing CNXI

Answer 14

Shrug shoulders (and resist) - TRAPEZIUS
Turn head to flex neck (and resist) - SCMD

Question 15

For CNXII, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 15

Descends lateral to carotid sheath (at hyoid turns anteriorly to tongue)
Pass anteriorly to hypoglossal canal
Many rootlets lateral to pyramids of medulla

Question 16

Outline how you would go about testing CNXII

Answer 16

Stick tongue out and move side-side

Tip of tongue will point towards side of pathology

Question 17

For CNV, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 17

Sensory passes superficial to deep structures of face posteriorly to foramen
Motor from CNV3 travels from f. ovale to skeletal muscle

Inferior to tentorium cerebelli

Pons!

Question 18

Give the superficial sensory divisions for the trigeminal supply to the face

Answer 18

CNVI: upper eyelid to tip of nose to forehead
CNV2: Lower eyelid to upper lip and nostril
CNV3: Lower lip and chin to TMJ/ mandible (except angle)

Question 19

What gives sensory supply to the angle of mandible, and what are the roots of this nerve?

Answer 19

Great auricular nerve (C2, C3)

Question 20

Give the deep sensory divisions for the trigeminal supply to the face

Answer 20

CNV1: orbit (not floor or lower eyelid), upper anterior nasal cavity, paranasal sinuses (not maxillary), anterior and posterior CF

CNV2: lower posterior nasal cavity, maxillary sinus, maxilla, floor of nasal cavity/ palate, maxillary teeth, soft tissues

CNV3: Middle CF, mandible A 2/3 of tongue, floor of mouth, buccal mucosa, mandibular teeth

Question 21

Outline how you would go about testing the sensory divisons of CNV

Answer 21

Close eyes
Cotton wool - ‘Say when you feel me touching you’
Compare sides

Question 22

Which nerve is the 1st part of afferent limb of blink/ corneal reflex?

Answer 22

Long ciliary nerve

Question 23

Outline how you would go about testing the motor division of CNV

Answer 23

Palpate strength of masseter (clench teeth)

Open jaw against resistance

Question 24

For CNVII, give it’s extracranial and intracranial course and connection with CNS (if applicable)

Answer 24

Somatic motor fibres to parotid gland and then facial expression muscles (1 out of 5)
Directly to IAM
Pontomedullary junction

Question 25

The facial canal is located within what part of the temporal bone?

Answer 25

Petrous part

Question 26

What is the function of chorda tympani, a branch of CNVII?

Answer 26

Taste to A 2/3 of tongue | PS to submandibular and sublingual glands (salvation)

Question 27

What is the tiniest SkM in the body?

Answer 27

Stapedius

Question 28

What is the role of the stapedius muscle, and what happens when you damage it?

Answer 28

Reduces stapes movement to dampen down excessive noise | Hyperacuisis

Question 29

Outline how you would go about testing CNVII

Answer 29

Test the muscles of facial expression - raise eyebrows, close eyes tightly, smile, puff out cheeks and hold air

Question 30

List the muscles of facial expression

Answer 30

Frontalis Orbicularis oculi Elevators of lips Orbicularis oris

Question 31

For CNIX, give it's extracranial and intracranial course and connection with CNS (if applicable)

Answer 31

Descends in pharynx in mouth to stylopharyngeus, parotid gland, pharyngeal muscosa, carotid body and sinus, posterior 1/3 of tongue Directly to jugular foramen Medulla oblongata

Question 32

Outline how you would go about testing CNIX

Answer 32

Elicit afferent limb of gag reflex

Question 33

What is the only muscle supplied by CNIX

Answer 33

Stylopharyngeus

Question 34

Which muscles are supplied with motor innervation from CNV?

Answer 34

Tensor tympani Tensor veli palatini 1 pair of jaw closing muscles - lateral pterygoid 3 pairs of jaw opening muscles - masseter, temporalis, medial pterygoid

Question 35

For CNX, give it's extracranial and intracranial course and connection with CNS (if applicable)

Answer 35

Structures between pallate and midgut Directly into jugular foramen Medulla oblongata

Question 36

Why is pain often referred from pharynx to ear and vice versa?

Answer 36

Both supplied by glosopharyngeal nerve

Question 37

What two vessels is the carotid sheath located between? Which CN runs in the carotid sheath?

Answer 37

CCA and IJV | Vagus nerve

Question 38

The left recurrent laryngeal nerve, branch of CNX, passes under...

Answer 38

Arch of aorta

Question 39

The right recurrent laryngeal nerve, branch of CNX, passes under...

Answer 39

Right subclavian artery

Question 40

Outline the route taken by both vagus nerves from the chest to abdomen

Answer 40

``` RIGHT: Lateral aspect of trachea LEFT: Lateral aspect of aortic arch Pass posterior to lung root on oesophagus Pass through diaphragm with oesophagus Pass onto surface of stomach Branches and travels to organs ```

Question 41

List the branches of the vagus nerve in the abdomen

Answer 41

``` Celiac and superior mesenteric ganglia Foregut Renal Midgut (on mesenteries) Splenic Pancreatic ```

Question 42

What vertebral level do the oesophagus and vagus nerve pass through the diaphragm?

Answer 42

T10

Question 43

Where do the vagus nerves very last PS axons pass onto?

Answer 43

Splenic flexure of colon

Question 44

Outline how you would go about testing CNX

Answer 44

MUSCLES OF PALATE (motor) - Say 'aaah' - uvula deviates to side that is functioning PHARYNGEAL MUSCLES - Swallow water and see if they splutter LARYNGEAL MUSCLES - Listen to speech and see if any hoarseness

Question 45

Which CN is the only nerve to exit the brainstem posteriorly?

Answer 45

Trochlear nerve - EXIT POSTERIOR MIDBRAIN AT JUNCTION WITH PONS

Question 46

If a patient has reduced sensation unilaterally on the face, including the forehead and lip, what does this suggest? Why?

Answer 46

More likely involves peripheral facial nerve (Bell's palsy) than a central lesion (forehead sparing) There is bilateral innervation of the upper facial nerve

Question 47

Which cranial nerves are located within the cavernous sinus and can be damaged in thrombosis?

Answer 47

III, IV, VI, V2, V1

Question 48

Outline the 'rule of 4' for cranial nerves

Answer 48

4 above the pons (1-4) 4 at the pons (5-8) 4 in medulla (9-12)